CVE-2026-11717
Google Cloud Platform OAuth Authentication Bypass
Description
An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), the toolbox decodes the response into an introspectResp struct where the Active field is declared as a pointer to a boolean (*bool). The code only explicitly rejects a token if the response contains a populated active field set to false (if introspectResp.Active != nil && !*introspectResp.Active). If an introspection endpoint responds with a payload that completely omits the mandatory active key, the internal variable remains nil, causing the conditional check to short-circuit. As a result, Toolbox accepts authorization tokens missing the "active" field, granting access to protected tools and underlying data sources.
INFO
Published Date :
June 18, 2026, 2:17 p.m.
Last Modified :
June 22, 2026, 8:18 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | CRITICAL | 14ed7db2-1595-443d-9d34-6215bf890778 | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Ensure the 'active' field is mandatory in introspection responses.
- Modify the validation logic to treat missing 'active' as false.
- Update the googleapis/mcp-toolbox library to the latest version.
Public PoC/Exploit Available at Github
CVE-2026-11717 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-11717.
| URL | Resource |
|---|---|
| https://github.com/googleapis/mcp-toolbox/pull/3341 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-11717 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-11717
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
None
Shell
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-11717 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-11717 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by [email protected]
Jun. 18, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Google', 'product': 'MCP Toolbox for Databases (googleapis/mcp-toolbox)', 'versions': [{'status': 'affected', 'version': '1.0.0', 'versionType': 'semver', 'lessThanOrEqual': '1.3.0'}], 'defaultStatus': 'unaffected'}] Added Description An authentication bypass vulnerability exists in the generic opaque token validation path (validateOpaqueToken) of googleapis/mcp-toolbox. When verifying an unparsed opaque token via an OAuth 2.0 introspection endpoint (RFC 7662), the toolbox decodes the response into an introspectResp struct where the Active field is declared as a pointer to a boolean (*bool). The code only explicitly rejects a token if the response contains a populated active field set to false (if introspectResp.Active != nil && !*introspectResp.Active). If an introspection endpoint responds with a payload that completely omits the mandatory active key, the internal variable remains nil, causing the conditional check to short-circuit. As a result, Toolbox accepts authorization tokens missing the "active" field, granting access to protected tools and underlying data sources. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-287 Added Reference https://github.com/googleapis/mcp-toolbox/pull/3341 -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-11717', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-18T12:23:05.330652Z'}